There is known a head mounted display apparatus (a head mounted display (HMD)), which is a display apparatus mounted on the head. For example, the head mounted display apparatus generates, using a liquid crystal display and a light source, image light representing an image and leads the generated image light to the eyes of a user using a projection optical system, a light guide plate, and the like to thereby cause the user to recognize a virtual image.
PTL 1 describes a system for improving display of information in a medical environment using such a head mounted display apparatus. In the technique described in PTL 1, information is acquired from a plurality of information sources on the basis of a query. The acquired information is subjected to filter processing on the basis of rules and projected on eyepieces of an eyeglass headset-type viewer. In the technique described in PTL 1, a control right and a priority right concerning display of a fixed large display are determined on the basis of the visual line of a wearer of the head mounted display apparatus. PTL 2 describes a face mounted video display apparatus for medical use (a head mounted display apparatus). In the technique described in PTL 2, operation state information of endoscope peripheral devices used together with an endoscope during an endoscopic examination or an endoscopic surgery is displayed on the head mounted display apparatus. PTL 3 and 4 describes a method for performing display of information in a dental surgery by applying an augmented reality technique in the head mounted display apparatus. In the technique described in PTL 3 and PTL 4, a preoperative image, a simulation image, and the like are displayed to be superimposed on an actual image of a site of operation.